Wall surface transducer system

ABSTRACT

A transducer assembly for mounting on a wall surface or other surface for converting electrical energy to sound or vice versa. The invention is an improvement on prior art devices of similar character in providing improvement in frequency response and truer sound reproduction. The improvement comprising a housing formed from two cup-shaped members whose edges of peripheral joinment are curved surfaces, the curvature of said surfaces being identical, equal, and complementary to each other. Consult the specification for other features and details of the invention.

United States Patent [111 3,567,870

[72] Inventor Beniguo A. Rivera 2,883,459 4/1959 Roy l79/2.5

Rio Piedras, P.R. 3,113,633 12/1963 Eberhardt et a1. 179/1.3 [21] Appl.No. 747,699 3,221,296 11/1965 Milne 340/10 [22] Filed July 25, 19683,369,078 2/1968 Stradley 340/10 [45] Patented Mar. 2, 1971 3,430,0072/1969 Thielen 179/1 15.5 [73] Asslgnees Harold Linden; PrimaryExaminer-- Kathleen H. Claffy Lawrence Gordon Arsistan! Examiner.lonBradford Leaheey San Juan Att0rney--Beveridge and De Grandi WA [54] LLSURFACE TRANSDUCER SYSTEM ABSTRACT: A transducer assembly for mountingon a wall 4 Claims, 5 Drawing Figs.

surface or other surface for converting electrical energy to U.S. soundor vice versa The invention is an improvement on prior Cl H041 artdevices of similar character in providing improvement in [50] 0f Searchfrequency response and truer ound rep oductior The im- 340/10, provementcomprising a housing formed from two cup-shaped members whose edges ofperipheral joinment are curved sur- [5 6] References cued faces, thecurvature of said surfaces being identical, equal, and UNITED STATESPATENTS complementary to each other. Consult the specification for2,479,072 8/ 1949 Lee 179/1 15.5 other features and details of theinvention.

PATENTEU MAR 2 Kill SHEET 2 [IF 2 ha I E INVENTOR BENIGNO A. RIVERA BYEMM? ATTO NEYS WALL SURFACE TRANSDUCER SYSTEM The present inventionrelates to a wall surface mounted transducer device and system and moreparticularly to an improvement in such devices for producing a truerreproduction and more uniform frequency response.

There is presently available sound transducers which do not have thenormal paper diaphragm for translating voice coil movements of anacoustical diaphragm or pump. Such devices are mounted upon a wall orother surface by screws and the like devices and couple acousticalenergy directly to the wall surface so as to excite or vibrate the wallin accordance with the acoustical energy and thereby produce sound.Fidelity and frequency response of such devices while adequate for somepurposes, do not have a true sound reproduction and the frequencyresponses are not uniform. This lack of fidelity and frequency responseis believed to be due, at least in part, to the fact that prior devicesutilized housings the coupling walls of which are relatively plainfrustums of cones joined base to base, which it is believed introducedistortion in coupling of the translated or transduced energy to thewall surface per se and vice versa. Accordingly, an object of thepresent invention is to provide a sound transducer which has a truersound reproduction and more uniform frequency response. A further objectof the invention is to provide such a unit for use in connection with asystem for remotely exciting wall surfaces utilizing conventionalalternating current wiring in a house, for example.

The above and other advantages, features and objects of the presentinvention will best be understood by reference to the followingdescription taken in connection with the accompanying drawings in which:

FIG. I. is a partial cutaway section of a top plan view of a wallsurface sound transducer constructed in accordance with the invention;

FIG. 2 is a cross section elevation view taken along the lines 22 ofFIG. 1;

FIG. 3 is an isometric view of the voice coil of the invention;

FIG. 4 is a partial cross-sectional view showing one mountingarrangement; and

FIG. 5 is a schematic block diagram showing the invention as utilized inconjunction with a system for remotely exciting a plurality of wallsusing conventional alternating current house wiring.

With reference now to FIGS. 1 3 of the drawings, a sound transducerconstructed in accordance with the present invention comprises a moldedcup-shaped base member 10, a molded cup-shaped cover member 11, magnetassembly 12 and coil assembly 13, connected by leads 14 to terminals 16passing through apertures or slots 17 to the exterior of molded basemember 10.

Base member and cover member I] are preferably molded from apolycarbonate resin such as Lexan or nylon, for example. Base covermember 10 has molded integral therewith mounting hub 18 projecting fromthe axial center of its exterior surface 19. A threaded metal insert 20is molded in or otherwise secured in a central bore 21 in mounting hub18. A wall, which it is desired to excite, is prepared by driving athreaded screw (not shown) or otherwise adhering a like threaded memberto the wall in projecting relation therefrom and then threading sameinto threaded insert 20 so that hub end 22 is in snug and flush abutmentwith the wall surface (see FIG. 4).

On the opposite side of housing 10 from mounting hub 18 is a cylindricalvoice coil form or cylinder mounting hub 23 to which the end of voicecoil form 24 telescopes over and is secured thereto by an adhesive, suchas an epoxy adhesive.

Spaced radially from mounting hub 18 is a thickened portion 19 of basecover member 10 which is annularly shaped and concentrically disposedabout hub 18. An outer annular groove 16 and an inner annular groove 27in effect renders the thickened portion 19 a corrugated structure toafford sufficient flexibility that audio energy being coupledtherethrough is substantially undistorted.

Cover member 11 is molded to have an enlarged magnet assembly receivingrecess 30 defined by an annular rib 31. The magnet assembly comprises acore 32 having a reduced portion 33 integral therewith and onto reducedshoulder portion 3, keeper washer 34 is force fitted or otherwisesecured to form uniform magnetic circuit. A relatively large ferritemagnet 36 is secured by an annular rib 37 of adhesive such as epoxyadhesive (for example) to keeper washer 34 and ferrite magnet 36 has anaxial opening or hole 38 which is coaxially centered with magnet core32. A shim 39 is placed between the shoulder 40 and keeper washer 34.Keeper washer 41 is adhesively secured to ferrite magnet 36 by an epoxybead 42 and has an opening or hole 43 through which the end of magnetcore 32 passes whereby the end 44 of magnet core 32 is flush with theouter surface 46 or keeper washer 4]. Aperture or hole 43 and keeperwasher 41 is slightly larger than the diameter of core part 32 to permitpassage of voice coil assembly 13 into position in the magnetic gapbetween the walls of hole 43 and the outer surfaces of core member 32.In this way, large magnetic fluxes are concentrated into the gap wherethe voice coil assembly 13 is located.

Keeper washer 34 is secured in recess 30 by an epoxy adhesive. Magnetassembly 12, being secured by the epoxy securement of keeper washer 34in the recess or chamber 30, is relatively stationary, the coil form 24is secured to coil form hub 23 which is opposite to mounting hub 18 sothat is moves relative to the magnet assembly 12. Keeper washers 34, 41and core 32 are galvanized or otherwise coated to reduce hysterisislosses.

An important feature of the invention is in the coupling of relativevibratory movement between the large mass of the magnet assembly 12 andcoil assembly 13 to mounting hub 18 in as distortion free a manner aspossible. In accordance with the invention, this is accomplished byproviding smoothly curved and uniform surfaces between annular rib 30 oncover member I] to annular rib 50 on base cover member 10. To this end,the outer surface 51 of base member 10 and the outer surface 52 of covermember 11 have a common axis of revolution and are curves generatedabout a common radius and revolved about a common axis coaxial. In otherwords, surfaces 51 and 52 constitute a toroidal motion-coupling memberfor relative translatory movements between magnet assembly 12 and coilassembly 13. Inner surfaces 53 on base cover member 10 and inner surface54 of cover member 11 have smoothly curved surfaces of equal radius but,as shown, are traced or generated from offset centers so that thethickness of the motion-coupling members gradually increases to the lineof jointment 56 between the two members. As shown, to accommodatemanufacturing tolerances the edges of the members are beveled as at 56and have complementary mating surfaces as at 57. An epoxy adhesive, forexample is utilized to join the peripheral edges at the complementarymating surfaces. By eliminating any abrupt changes in the motioncouplingsections of base member 10 and cover member 11 a flatter (more uniform)and wider frequency response is achieved and a source of distortion iseliminated.

The voice coil 13 assembly (as well as magnet assembly 12) is ofconventional construction in that it comprises an insulating cylinder orform 60 wound with or having secured thereto a conventional voice coil61 having leads 14 which are held adjacent to insulating cylinder 60 bya tape or other insulating material 62. The end 63 of cylinder 60 istelescopically fitted on shallow hub 23 and secured thereon by adhesivesuch as an epoxy glue.

The transducer can be mounted on a variety of surfaces, the most commonand best including wood, glass, plastic, dry wall, plaster, etc., metal,acoustical tile, or almost any flexible not rigid structure. The unit ispreferably not mounted directly over studs, joists, etc., but ispreferably mounted between such structural members. While the unit iseffective for most surfaces, brick, concrete, or stone surfaces are forthe most part too rigid.

It will be appreciated that while the transducer has been describedabove primarily in connection with producing sound energy as for examplewhere electrical currents corresponding to audio energy are supplied tovice coil 13 which then through the relative translatory movements ofmagnet as sembly l2 and the coupling of such movement via the couplingmembers described earlier herein to hub 18, excite a wall so the wallserves in effect as an acoustical diaphragm to produce audio energy, thetransducer unit of the present invention may also be utilized inconverse manner, namely, by connecting a sensitive amplifier to leads 14of the voice coil assembly the unit may be utilized to detect sounds ina room in which the unit is mounted and thus may serve as a sensor forburglar alarm or other listening system where the transducer constitutesa listening device.

It will also be appreciated that various forms of securement to a wallor other flat planar surface may be effected. For example, a small plate20? having a screw 20S adapted for threaded engagement with insert 20(FIG. 4) may have the base there adhesively secured to a glass plate orwindow wall 20W, for example, and such window wall can then be excitedto produce an acoustical output.

The invention is well adapted to excite interior and exterior nonmasonrywalls and, being substantially waterproof, is well adapted for outdooruse. Carrier frequency wire-broadcasting systems utilizing conventionalpower lines within a building for distribution of signals such as audio,radio broadcast signals and stereo systems, alarm systems and the likeare well known. FIG. illustrates an adaptation of this systemincorporating the transducer of the present invention to remotely excitea wall with acoustic energy. Thus, a program source, such as Hi Fi set70 supplies an audio output to a mixer-amplifier 7] which receives as asecond input (as a carrier frequency) an output from a low frequencycrystal oscillator 72 which is modulated by the audio signal from Hi Fiset 70. A coupler 73, which may be a transformer, capacitances, or otherknown coupling devices, applies the thus modulated carrier signal fromoscillator 72 to a pair of conductors 74 having a male plug 76 adaptedfor insertion in female convenience outlet 77 which may be in a wall inthe room having the Hi Fi set 70. A rectifier 78 converts alternatingcurrent power delivered thereto from leads or conductors 74 to directcurrent and supplies same to oscillator 72 and mixer amplifier 71. Inthis way, which is, per se, conventional, an entire house-wiring systemis adapted as a means for coupling the audio output of Hi Fi set 70 toany room in the building, such as a home. Wiring 79, 80,

and 81 are conventional alternating current wiring to recepta-.

cles 82 and 83, respectively, so that there is presented at each ofthese convenience outlets 82 and 83 a carrier frequency from oscillator72 modulated with the audio signal from Hi Fi sets 70. A receiver unit84 is provided with conventional male plug 86 and conventional wiring 87and a filter-coupler such as coupler 88, which may be a transformer (notshown) having a filter (not shown) for blocking the 60 cycle alternatingcurrent supply. Filter-coupler 88 passes the modulated carrier fromoscillator 72 to detector 89 which produces an output corresponding tothe audio signal from Hi Fi set 70. This audio signal is then applied toan audio amplifier unit 90 the output of which is applied to transducer91 constructed in accordance with the invention and mounted upon a wall92 in the manner illustrated diagrammatically in FIG. 4A. This systemmay be operated in a stereo system in which there would be a secondchannel, each channel being transmitted on a different frequency,respectively, and coupled to house wiring 79 in the mannerdiagrammatically illustrated in FIG. 5. The modulated RF output coupledto house wiring 79 to convenience outlets 82 and 83, for example, isextracted by a simple plugging in a male plug 86 at any such convenienceoutlet and then capacitively coupled through a filter unit 38 todetector 89 (which may be a tuned RF detector), the output of which isapplied to an audio amplifier which in turn applies the audio signal totransducer 91 to excite the wall with acoustic energy as describedherein. For the stereo system, a

second transducer may be mounted on the wall in spaced relation from thefirst transducer to effect stereo reproduction. In

this case, of course, audio source 70 would be a stereo Hi Fi set, astereo receiver, or a stereo public address system, it being understoodthat at each output of the stereo audio unit 70 is frequency translateda different frequency for coupling to the house wiring 79.

As diagrammatically illustrated in FIG. 5, since the entire house wiringis a conductor for the modulated carrier signals, units may be excitedremotely in any room of the structure building or home simply byproviding a second unit such as shown in the lower left-hand corner ofFIG. 5.

While a preferred embodiment of the invention has been shown anddescribed, it is to be understood that the invention is susceptible touse in many systems, some of which have been referred to above and withvarious modifications within the scope of the appended claims.

Iclaim:

I. In a surface-mounted transducer device wherein an annular magnetassembly has positioned for axial movement in an annular air gap thereina coil adapted to be connected to electrical terminals, and a housinghaving a first cup-shaped member to which said annular magnet assemblyis secured and the second cup-shaped member to which said coil issecured, said cup-shaped members having substantially flat planarparallel surfaces, said cup-shaped members being joined along theperipheral edges thereof, said second cup-shaped member having a singlesecurement point coaxial with said coil and spaced from the outersurface of said second cup member and secured to an engaging transducermounting surface, the improvement comprising surfaces of said cup-shapedmembers leading to said edges of peripheral joinment being curvedsurfaces, the curvature of said surfaces being identical, equal andcomplementary to each other.

2. The invention defined in claim 1, wherein the radius curvature ofsaid surfaces is about a fixed axis common to both said surfaces.

3. The invention defined in claim 2, wherein the radius of curvature ofboth surfaces is about a common fixed surface and surfaces formedthereby having a common axis of revolution.

4. The invention defined in claim 1, wherein the said cupshaped membershave graduallyincreasing thicknesses along said curved surface portionsto said point of joinment.

1. In a surface-mounted transducer device wherein an annular magnetassembly has positioned for axial movement in an annular air gap thereina coil adapted to be connected to electrical terminals, and a housinghaving a first cup-shaped member to which said annular magnet assemblyis secured and the second cupshaped member to which said coil issecured, said cup-shaped members having substantially flat planarparallel surfaces, said cup-shaped members being joined along theperipheral edges thereof, said second cup-shaped member having a singlesecurement point coaxial with said coil and spaced from the outersurface of said second cup member and secured to an engaging transducermounting surface, the improvement comprising surfaces of said cup-shapedmembers leading to said edges of peripheral joinment being curvedsurfaces, the curvature of said surfaces being identical, equal andcomplementary to each other.
 2. The invention defined in claim 1,wherein the radius curvature of said surfaces is about a fixed axiscommon to both said surfaces.
 3. The invention defined in claim 2,wherein the radius of curvature of both surfaces is about a common fixedsurface and surfaces formed thereby having a common axis of revolution.4. The invention defined in claim 1, wherein the saiD cup-shaped membershave gradually increasing thicknesses along said curved surface portionsto said point of joinment.